Algebra 2.8Percents

Learning Targets

Language Goal•Students will be able to verbally express

numbers written as percents.Math Goal•Students will be able to solve problems

involving percents.Essential Question•Where do you use percents in the world

around you?

Warm-up

Homework Check

Homework Check

Vocabulary1. A value of the variable that makes the equation true  2. An equation that is not true for any value of the variable. It has no solution. 3. An equation with two or more variables. To solve for one of the variables, use inverse operations. 4. A ratio that compares two quantities measured in different units 5. The ratio of two equal quantities, each measured in different units. 6. In the statement, , where bc and ad are the ?

Solution of an equation

Contradiction

Literal Equation

Rate

Conversion Factor

Cross products

Vocabulary1. A mathematical statement that two expressions are equal 2. An equation that is true for al values of the variable 3. An equation that states a rule for a relationship among quantities. 4. A comparison of two quantities by division 5. A rate in which the second quantity in the comparison is one unit 6. A statement that two ratios are equal;

Equation

Identity

Formula

Ratio

Unit Rate

Proportion

Vocabulary

•Percent:

A ratio that compares a number to 100.

Changing Percents to Fractions

•Take the percent and put it in the numerator spot.

•All percents are out of 100. So use 100 for the denominator.

•Simplify/Reduce the fraction.

Changing Percents to Decimals

•Move the decimal point two spaces to the left.

25% = .25

Here are common Percents!

Example 1: Finding the Part

•There will be two methods▫1. Using a proportion▫ or

▫2.Use an equation x = (% written as a decimal)(#)

Example 1: Finding the Part

•Method 1: or

A. Find 50% of 20 B. Find 20% of 60 C. Find 210% of 8

Example 1: Finding the Part

•Method 2: x = (% written as a decimal)(#)

A. Find 105% of 72 B. Find 4% of 36 C. Find 300% of 3

Example 2: Finding the percent

•Method 1: or

A. What percent of 60 is 15? B. 440 is what percent of 400?

Example 2: Finding the percent

•Method 2: x = (% written as a decimal)(#)

A. What percent of 35 is 7? B. 27 is what percent of 9?

Example 3: Finding the Whole

•Method 1: or

A. 40%of what number is 14? B. 40 is 0.08% of what number?

Example 3: Finding the Whole

•Method 2: x = (% written as a decimal)(#)

A. 120% of what number is 90? B. 48 is 15% of what number?

Example 4: Career Application• A. Jewelers use the karat system to determine

the amount of pure gold in jewelry. Pure gold is 24 karat, meaning the item is 100% gold. A 14-karat god ring contains 14 parts gold and 10 parts other metal. What percent of the ring is gold? Round your answer to the nearest percent.

Example 4: Career Application• B. Use the information before to find the

number of karats in a bracelet that is 42% gold. Round your answer to the nearest whole number.

Shopping Examples

•The regular price of an ipod is $209. If you have a student id you can save 10%. 1. How much money do you save?

2. What is the final price of the ipod?

What is 10% of $209?

Restaurant Example:

•You are going to eat at your favorite restaurant with a group of your friends. You get your bill back and your bill is $8.45. You want to leave a 18% tip. What is the final cost of your bill including tip?

Shopping Example:

•The sale price of a pack of socks is $6 off after a 10% discount. You want to know the original price?▫$6 is 10% of what number?

Extension Proportion Review

1. 2. 3.

Station Time

Lesson Quiz